When Amortentia Fails
by orionshuntingdog
Summary: Potterlock AU. It's extreme, perhaps immoral, but not all together shocking that Mary Morstan resorts to spiking Sherlock Holmes with a love potion for Molly Hooper; a catalyst for them to finally make sense of their feelings for one another. The real shock comes when the potion doesn't work, and what that means for the both of them.
1. I

**A/N:** **Hey, thanks so much for clicking and reading! Supposed to be writing chapters for Chemical Defects (and perhaps also doing A levels...) but this idea grabbed me and refused to let go, and I just love Potterlock. Turned out a lott longer than I was expecting. I really hope I've managed to keep everyone – especially Sherlock damnit – from getting OOC, and that you enjoy it!**

 **And biggest biggest biggest thanks in the world to lilsherlockian1975 for beta'ing, she's such a lovely person and has been so massively helpful in improving my writing as a whole, I couldn't be more grateful.**

* * *

"Can everybody see the cauldron? Good, good..."

The fumes that fill the potions classroom are intoxicating, alluring in their weightlessness, and Mary tilts her head back, letting the warmth of the afternoon wash over her.

She notices the dreamy, lost looks across her classmates' faces with a chuckle, noting that red curtains combined with a complete lack of ventilation were really not the most worthwhile investments in student concentration.

Not Molly though. Her face is, as always, bright with focus; her back rigid with attention, absorbing Professor Slughorn's every word.

She makes an amusing contrast to the student beside her, who wears an expression of utter boredom as he leans slightly against the wall. Though his eyes are unfocused, on a trip to the mind palace no doubt – she snorts – she knows he is cataloguing every piece of information the room has to offer.

"Well, take a look, my dears!" Slughorn booms. "Don't be shy."

His theatrics have the desired effect; the students jostle forward, crowding eagerly around the cauldron. With minimal movement (damn him for being so tall), Sherlock's frankly unimpressed stare flickers over the cauldron's contents.

Mary elbows her way ruthlessly to the front and peers in with interest. She flits through her mental catalogue of potions as she tries to identify it - the mother-of-pearl sheen and the steam rising in spirals are distinctly familiar…

She meets Sherlock's eyes with a smirk she realises exactly what is in that cauldron, and he rolls his eyes at her, mouthing – _predictable._

Molly is still stuck at the back, grimacing as she attempts to wriggle through the throng. Mary winces as she watches the shortness her friend has long complained of prove distinctly detrimental to her efforts.

Until Sherlock reaches over, unceremoniously shoving Amos Diggory to the side. His hand presses ever so lightly at Molly's back, guiding her to the front.

 _Like clockwork._ Mary hides a smile.

"Thanks," Molly murmurs gratefully, her face slightly pink as she smiles up at him, before leaning forward.

Mary doesn't miss the way his mouth opens and closes, as though he is stumbling over a thought, before he carefully schools his expression once more.

"Amortentia!" Slughorn announces with relish, making a grand sweeping gesture to the cauldron in front.

Mary rolls her eyes as crude jokes and giggles filter across the classroom.

Molly's eyes widen excitedly, and Mary stifles a giggle herself as her friend practically gets up on tiptoes to see it – her enthusiasm is almost infectious. Once again, she doesn't miss the way Sherlock's face softens for a moment as he looks at her, an amused smile tugging at his lips.

"And who can tell me what it does?"

Molly raises her hand tentatively. Slughorn beams."Ah, Miss Hooper?"

"It's the most powerful love potion in the world." She hesitates, then persists, "Well, so-called love potion."

"Oh, ho!" Slughorn's eyes twinkle, and he asks genially, "Why "so called"?"

"Because..." She starts out quietly at first, but becomes more assertive with every word. "It's impossible to create love. Love–it sort of... _grows_ from something, until it fills you up."

Her eyes seem far away, and a little sad. Mary's heart fills with compassion for her friend, not out of pity (never pity), but pride at her enduring spirit, and a kind of indignation that somebody so wise and so true could ever be made to feel unloved.

And Sherlock stares at her intently as she speaks, his eyebrows furrowed, his lips pressed tightly together, as though trying to unlock a puzzle in each of her words.

"All that potion does is create a crazed obsession...nothing like the real thing, and a pretty poor substitute." She finishes simply, her hands falling to her sides, a spell of solemn silence cast over the room.

Then she rushes to add, "But I can't wait to study it."

Mary grins at her across the cauldron, mouthing - _good save_ – and Molly smiles sheepishly back. The spell is broken, and the light-hearted frivolity that had temporarily left the room – as each person reminisced about one once loved, or a love that was yet to be felt - returns in full force.

"Indeed! And your explanation - couldn't have said it better myself." Slughorn says warmly,

"Twenty very well-deserved points to Hufflepuff." And Molly flushes with pleasure.

At the sound of the Professor's voice, Sherlock's face falls back into its previous disdain. His gaze wanders over to a nearby shelf, where he examines the newest titles on the wall.

Slughorn continues gravely, "In fact, this lust filled little potion here is the most dangerous one in the room –"

"Hardly." Sherlock's scoff carries across the whole room, and the room collectively winces.

Slughorn turns towards him with obvious reluctance. "Holmes." He acknowledges wearily; these situations are too close to becoming routine.

Mary sends an intense glare Sherlock's way; she secretly finds his "verbal takedowns" hilarious, but Ravenclaw is narrowly in second place in the House Cup and she really doesn't want to see her hard earned Quidditch points go down the drain.

He ignores her pointedly, opens his mouth with relish, but then he catches sight of Molly's pleading look, her minute shake of the head, and promptly closes it again.

"Nothing, sir." He mutters reluctantly, looking away in irritation.

"Really?" Slughorn seems to have been bolstered by his most irritating student's apparent retreat, his chest puffs up, and he continues with triumph. "Not entirely surprised, m'boy. Paying hardly any attention, stood there with that sullen look on your face, it's no wonder you have nothing to say."

Silence.

Mary runs her hands across her face, and for an instant she fools herself that Sherlock has developed temporary deafness, or perhaps an even more temporary sainthood; any way for him to just let the words float by.

It seems as though the room itself holds its breath.

Slughorn has turned back to the blackboard, writing up the brewing method, completely unaware of the chaos about to erupt. It is his biggest mistake.

Sherlock's head snaps up, and there is not a single glimmer of outrage or anger on his face. There is only deathly calm. His eyes rest on the Professor's back, filled with a single minded ruthlessness.

And Mary knows then that Slughorn is doomed.

"Well, Horace, if you're looking for an answer, I'll give you one." His eyes flash, and the words are precise and piercing. "Amortentia, as Molly said, does nothing more than simulate foolishly blind infatuation, something that people are more than happy to create for themselves at a moment's notice. So yes, I'd say labelling a sex drink as threatening is ambitious, but "most dangerous potion in the room?"

Mary looks over at Molly, who has her hand over her face – at first glance she seems pained, but it soon becomes apparent she is both trying and failing to hide a smile.

Sherlock snorts, and his voice is incredulous. "Melodramatic, even for you. The only use it has for me is in generating the smells of books, the black lake, burning wax, some Muggle chemicals and –" A flicker of confusion crosses his face, so quickly smoothed over it is almost impossible to notice, but she doesn't miss it.

"- and on closer observation," His voice takes on a hard edge, and he makes a show of slowly looking him up and down. "It's not surprising at all that you chose to focus on a _love potion_ , considering you've been rejected by two witches and a wizard in the last month."

He rolls his eyes at the gasps that echo around the room. "Oh please, it's not as if he ever confined himself to one gender when he "collected" his students. All further evidence of his wallowing in self pity; if the closest thing he has to meaningful relationships are the students in the framed photos on his wall, which he takes _religiously_ good care of – judging by the depth of dust – then perhaps I shouldn't begrudge you trying to console yourself with a _love potion_." He crosses his arms. "Except, yes, yes I do, because it's a complete and utter waste of our time."

Slughorn's face has turned an alarming shade of red, one that spreads further and further to his neck the longer Sherlock speaks. Beads have broken out on his forehead, and Mary almost pities him.

"Unacceptable!" he splutters. "The nerve, and the complete lack of decorum-" Heavy breaths escape him, and he temporarily seems to have lost the ability to formulate a sentence.

"Ninety points from Ravenclaw!" he shouts angrily, and Mary loses any pity she had for the professor, and any amusement she had felt for Sherlock's antics.

Cries echo around the room from their fellow Ravenclaws, the usual angry whispers of "Piss off Holmes!", "Bloody tosser!" and "Can't you just shut the hell up for once?" whilst the Hufflepuffs look gleeful.

The list of ways Mary has devised to kill Sherlock Holmes increases from thirty to fifty nine in a second.

But then something distracts her from her irritation. Unnoticed, Molly has backed away to the edge of the room, her face seems pale, blanched, and she pulls at the sleeves of her robes. As soon as she catches Mary's concerned glance, however, she immediately regains her former ease, giving her a quick smile before looking away.

It's interesting, the way the both of them seem so determined to portray specific facades, ones that Mary never buys, not for a second.

"...deserve to be in this lesson," the professor was declaring, and Mary sighs, refocusing her attention again on the utter hyperbole that is Horace Slughorn. "I demand you leave my classroom immediat –"

Sherlock lifts a single finger languidly, and at that exact moment the bell rings.

Mary stays behind momentarily to hunt for a quill she'd dropped, hearing snatches of conversations alternating between excited chatter and grumbled whispers on the events of the lesson. She catches up with her friends bickering light heartedly as they walk through the corridor outside.

" – and he claimed _I_ was the idiot. He had it coming to him, Molly!" Sherlock says defensively.

"Easy for you to say, you don't give a damn about the House Cup," Mary grumbles, punching him on the shoulder.

Sherlock wrinkles his nose at her, rubbing his shoulder as he mutters. "Still deserved it."

"I agree," Molly says apologetically to Mary, who opens her mouth in outrage to point out her house bias, and so she hurriedly turns back to Sherlock and tries, "I just think, maybe, you could have been a bit gentler, and I don't know, _not_ have taunted him about his love life?"

"Oh, well, apologies for impeding your application to the _Slug Club_..."

"Dear God, don't accuse me of wanting _that_." Molly looks positively revolted. "All those pretentious parties where I'd have to care about the invention of a potion that, oh I don't know, only makes someone's hair fall out a tiny bit slower."

That earns a rare laugh from Sherlock (actually, not so rare when it comes to Molly, Mary notes) and his face almost brightens from the full force of it.

"Spending a night dodging pervy fifty year old wizards – don't understand why you wouldn't want it, Molly," she teases in mock surprise, patting her on the shoulder.

Molly shudders. "I think I'd need your Defence against the Dark Arts expertise there."

"I think you may need to resort to your proficiency in Charms in order to cast an _Obliviate,"_ Sherlock quips; and they all dissolve into chuckles.

"But seriously..." Molly pauses, trying but failing to completely expel the laughter in her voice. "...it's not Slughorn I'm trying to defend, I'm just worried you won't get a potions NEWT at this rate."

Mary raises her eyebrows. "I'm sure his brother will put in a word for him," she says pointedly, and Sherlock nods complacently at her.

"Yes, having my very own King Slug really is a handy asset," he drawls, smirking as he dodges the hand that Mary swats at him.

Molly grins at him, and her gaze lingers on his face when Sherlock looks elsewhere. It softens, taking on a hint of the wistful, as delicate as drops of mildew on blades of grass. But then Mary sees her face blanch again as it did in the classroom, and she glances away.

"I've got an essay to do for McGonagall for next lesson, so I need to dash off," she says hurriedly, pulling her bag tighter over her shoulder, and rushes on ahead.

"Just copy Sherlock's," Mary calls. He turns to her with a questioning look, and she adds louder, "I already did, he had no idea!"

Sherlock's eyes narrow in disbelief, and she shrugs unashamedly.

"Unlike you, Morstan, I have morals!" Molly yells back over her shoulder, and Mary really cannot deny her point.

(Well maybe she can, but she has a suspicion that something is bothering Molly, something she needs time alone to process.)

Sherlock's stare comes to rest on the back of Molly's head, that transcendent softness returning to his face, almost catching him unawares.

In that moment, Mary instantaneously understands two things at once. She realises _exactly_ what is troubling Molly, _exactly_ what Sherlock is so unaware of, and that these two things are _exactly_ the same.

That familiar indignation bubbles up in her again, and she decides to bite.

"Perfume, was it?" she says nonchalantly.

"Sorry?"

"That smell you couldn't identify. From the Amortentia." She nods at Molly's retreating back."A sort of honeysuckle?"

Sherlock's eyes widen, a deep crease appears between his eyebrows, his lips pressing rigidly together. She can almost hear the gears turning in his mind, the clunk of the penny as it drops.

There's a sharp intake of breath, and then his mouth shuts as quickly as it opens. A scowl darkens his face.

"Oh piss off," he spits, pushing past her, and Mary grins.

* * *

Half an hour later she finds Molly in the library, her head in her hands, with _Trials of Transfiguration_ \- the recommended book for their essay – open on her lap.

Open on page one. _Bollocks._

Mary slides into the seat in front, and her friend looks up, her frown relaxing into a relieved smile as she identifies her.

"How's the essay?" she asks knowingly.

Molly looks decidedly shifty. "I've started it," she says slowly.

Mary glances at the page in front.

"Alright, I've written the title," Molly admits, gesturing to the words " _Partial corporal transfiguration"_ scrawled on an otherwise empty parchment. "So," she continues, banishing any troubling emotions on her face into a knowing smile. "What did you smell today?"

Mary allows her the temporary deflection. She leans back in her chair. "Butterbeer. Fresh fallen snow. A Quaffle. John's sweaty Quidditch robes right before I jump his bones," she finishes airily, and grins as Molly does a double take and bursts out laughing.

"Dear God, Mary Morstan, your libido is insatiable," she splutters, looking half amused and half scandalised.

Mary shrugs happily. "Those Quidditch robes just do it for me."

Molly laughs again, but Mary immediately hears its forced edge, its half-heartedness, how quickly it dies. Softly, she asks, "You got _his_ scent, didn't you? That's what's bothering you."

"God, that makes me sound like a dog," Molly lets out a deep breath, looking down at her intertwining fingers, the knuckles turning white against the mahogany of the table. "Yeah," she breathes out shakily, and finally meets Mary's gaze. Her eyes – they're so openly vulnerable, so heavy with an immeasurable ache that Mary almost can't bear to look.

 _Hands fist the shirt on her back. Wracking cries against her shoulder. Her heart beats into rage for a broken one._

 _And after it all, Molly wipes her tears in determination, and looks her fixedly in the eye._

" _I'm over him," she says fiercely. "Or I swear to you I will be. I'm done crying over him."_

 _Mary nods, only pulling her into another hug. They don't speak of it again._

"I'm so sorry, love." Her arm reaches across the table and gives Molly's a squeeze. She bites her lip, and says cautiously, "The potion's fumes are only attraction though, maybe –"

Molly shakes her head, and Mary's words fall flat.

"No." She pauses, turning her head to stare out into the grounds, towards the black lake, fiddling absentmindedly with her plait. Eventually she turns back to Mary, whose eyes never left her, and says quietly. "I've never needed a potion to figure out my feelings. I – I never got over him." Her teeth clench as frustration fills her voice. "I tried so _hard_. It was always there, no matter how I tried to ignore it, or pretend it wasn't. But I-"

Mary sees her body sag against her chair, and she sounds _so_ defeated that it kills her. "I love him, Mary."

"I know," she says honestly, and Molly bows her head. Mary's fingers reach out and tap under her chin, lifting her gaze up to hers. "It doesn't make you any less strong," she says determinedly, and Molly briefly smiles at her in gratitude.

"I learn to live with it. It's just today." She sighs, her face lapsing back into its previous dejectedness. "Having a physical reminder of your pathetic and hopeless feelings shoved in your face is a bit shit."

"It's not pathetic," she stresses. _And it's certainly not hopeless._ The words bubble up inside of her and she wants to share them so badly, but they cannot come from her.

(What Molly needs to hear can only come from one person alone.)

* * *

Mary notices many things. In the world she grew up in, missing the most minute of signs could cost you dear, and she was forced to learn quickly.

Now, she watches her friends spinning in circles so close to overlapping, sometimes only a sliver of a millimetre apart, but somehow constantly missing one another in their trajectories.

It's becoming unbearable to watch, because what Molly longs for (though she pretends she doesn't) is precisely what Sherlock feels (though he pretends he doesn't). So much make-believe - and all for what?

She decides it's Sherlock who needs the push, because Molly has acknowledged her feelings, but has decided to bear them all alone, whereas he doesn't have the self awareness to recognise them, or the understanding of what needs to be done in the aftermath.

For a man who feels so deeply, it's sometimes frightening how determined he is to lock his emotions away. Though as the sea erodes even the most hard wearing rock, so does she know that sentiment crumbles the cliffs of his cold resolve. That dreaded word has slowly but surely shaped him, smoothed his harder edges, made him softer somehow. Bit by bit, she's watched his feelings spill through the cracks of whatever door he has locked them behind.

Yet their emergence has never been voluntary, and he refuses to allow them the freedom they deserve. It's hurting Molly, and it's hurting him, and somehow he doesn't realise either of these things.

And perhaps a potion induced push in the right direction, him doing something, _anything,_ and seeing how right it feels, will remove this block he has, or at least force him to contemplate the possibility of coming to terms with it. If he crosses the line once, she hopes he will no longer be so afraid of it.

None of this justifies what she decides to do, but in a way, that is what makes it all the more appropriate. The solution couldn't be reasonable, for their crumbling dynamic was far from normal. It is slowly becoming a game of chess, both sides presuming to predict the emotional moves of the other's in an attempt to determine their own.

And Mary has never been content to sit on the sidelines of any game, far less one of which she can change the outcome.

So she steals back into the potions classroom, casts a Disillusionment Charm on herself (another skill learnt far too young for all the wrong reasons) and watches Slughorn marking essays at his desk.

He monologues to himself as he works, and it's truly an entertaining sight. There are over enthusiastic observations out loud at the good essays - he often takes sole credit for any talent in his students - whilst the bad ones illicit a melodramatic sigh with piteous mutterings. With some, he boldly claims that he'd always predicted a particular student's lack of prowess, even from the minute they walked into the classroom.

More importantly, however, the Amortentia is still rippling lazily in its cauldron, and Mary rather suspects Slughorn has left it out for it's invigorating aromas. Soon, he's consumed the appropriate amount of mead for an opportune bathroom break, and Mary loses no time in taking advantage of it.

A few minutes later, and Mary ducks out the classroom with her prize clutched in her hand, and a hair of Molly's she'd found earlier clutched in the other. The two are added eagerly together, and her eyes light up as the potion turns darker. _Activated_. Her jubilation is cut short as she realises hiding a flask under her robes may cross the line of the conspicuous into the flat out obvious, and so she stuffs it into her bag, hoping the lid is screwed on far more strongly than her patience.

She tiptoes into the Ravenclaw male dormitory – whichever founder had thought girls were more trustworthy was clearly the same person who'd thought hiding a monster in a chamber was a worthwhile assertion of power. What always strikes her when she visits is that, in spite of the stereotypes, this room is far neater than its female equivalent.

The framed poster of some Muggle chart she struggles to remember the name of (a peeryoddit table?) declares itself in its colours, bright against the pale wall, and she moves carefully towards the four poster bed beside it. Sherlock's bed is a microcosm of his mind; a cluttered mess of parchments and books and everything in between that he somehow insists has a system.

She raises her wand, and whispers, " _Accio Sherlock's jar of honey."_

The jar flies out of his second bedside drawer – so mundane he hadn't even considered it needed protection – into her outstretched hand.

The seemingly insignificant details, the ones he would probably delete from memory, are the ones she never forgets. She knows that once a month Sherlock receives this specific jar of honey from his parents - she can only assume it's something from his ever allusive childhood. And though he scoffs at their "overbearing mollycoddling", the honey becomes the main part of his diet until it runs out.

She unscrews the lid and pours the potion in, pulling her wand out to ensure that every detail is accounted for: the honey evenly mixed, its undisrupted shiny surface restored, and the lid promptly resealed afterwards. Under his scrutinising gaze, nothing can be left to chance.

Outside, the sun burns up its sky into dusk, and she stares at her reflection mirrored in the glass of the jar, warped, distorted, faint under the fading light. There is a moment of rare hesitation in this solitude, as she fully grasps for a moment exactly what this action could tear apart -

\- and exactly what it could tie together. That rises far more prominently in her mind, and she sets the jar back in its previous position with a magnified feeling of purpose, and an almost binding sense of duty.

* * *

It's depressing, Molly thinks, that these days Madam Pince sees far more of her than most of her friends.

It's the next day after breakfast, and the essay is still nowhere near done. Her head is slumped on her usual table, with ten books on human transfiguration scattered around her, the quill in her hand drooping listlessly.

"Still on this, then?" an all too familiar voice cuts through the fog in her brain; a voice that fills her with happiness for a moment and then becomes a poignant reminder.

She lifts her head blearily and looks up at Sherlock, his eyebrows raised and the faint traces of a smirk on his face – an expression that frustrates her in its ability to make her want to both punch him and kiss the living daylights out of him.

She huffs. "Well, some of us need longer than _a day_ to master a NEWT level transfiguration concept."

"Hmm," he drones. "Wasn't particularly a stretch." Holding his hands up at her glare, he says amusedly, "I did offer to show you."

"No," she insists, shaking her head stubbornly. "I will do it alone." A forlorn glance at the essay later, she admits, "Ask me again at the end of the week."

"Noted." He leans over her, and she swallows at his proximity, the scent of him almost intoxicating her, before she steadies herself in a matter of seconds. (It's becoming a well practised ritual.)

He plucks the essay out of her grasp and wrinkles his nose at it, grinning as he easily holds it out of reach of her scrabbling hands.

"Sherlock!" she yells, her arms extended. "Give. It. Back."

"This is a library, not a room of ruckus!" Madam Pince screeches in their direction.

"You heard the woman," he murmurs, holding a finger mockingly to her lips.

They are both still very quickly.

His skin is cool to the touch, and she can feel his pulse beating rapidly in the tip of his finger against her mouth. A burning heat rises within her, her lips part, and her breaths become shallower as she sees her face reflected vividly in his widened eyes.

He withdraws rather hastily, and turns away from her to tuck the essay into a pocket in his robes. When she sees his face again, she briefly searches it for any trace of unsettlement, any fraction of the turmoil she feels, but it is utterly composed, and that familiar sinking feeling surfaces in her stomach again.

Sliding into the chair opposite, he dumps a paper bag containing a lion's share of marmalade covered toast onto the table and pushes it towards her.

"Eat," he says simply. "It's illogical to think your brain will reach its maximum working capacity under starvation."

"You barely eat when you're working something out," she says, grateful but confused at this abrupt change in attitude.

"I wouldn't recommend being me," he says briefly, his eyes flickering for a moment, before he refocuses his gaze on her.

"Now eat," he commands, leaning forward on the table. "And tell me about something you actually find interesting."

Thoughtfulness in Sherlock comes and goes like the ebbs and flows of a tide, and she smiles as she pulls out the first piece of toast.

"I've been distracted lately by forensic pathology." Giggling slightly at Sherlock's bewildered look (it's a rarity to be savoured), she proceeds to clarify, "It's another branch of Muggle science."

His eyes light up, and he practically drums his fingers on the table in excitement. Being able to captivate him in concepts gives her a soft kind of pleasure, one that flows across her being, fills every crevice of her skin.

Molly, being Muggle-born, insisted on not completely abandoning her Muggle education. Her parents had obliged, sending her journals and articles by owl post. Ever since Sherlock had read a chemistry article over her shoulder at breakfast, he'd been completely riveted by the sciences and would frequently implore her for explanations at random intervals.

He never tells her the reasons behind his fascination, but then again Molly has never needed him to, and a multitude of them seem perfectly apparent to her. Growing up in one of the most noble pure-blooded families in Britain came, not necessarily with prejudice, but with a certain subconscious aura of scepticism around Muggle knowledge, and so finding distinctive evidence of the opposite must have seemed particularly thrilling.

Having, from childhood, long mastered a phenomenal level of magical understanding, this alternative dimension of entirely unfamiliar territory to explore must have seemed like a whole new world had opened up before his eyes, just as magic did for her.

What was most intriguing to the both of them, however, was the relationship between the two ideas. Whether they were two different theories for the same mechanisms, or whether magic flowed into science – the abstract into the tangible.

She nods happily and begins to explain. "It's basically working on the body after they've died. Mostly used to identify causes of death in a variety of ways: looking at the organs through dissection, or running tests to see what substances were inside them. So being able to tell whether someone offed themselves or – "

"- if they were murdered," he finishes in fascination, his face practically gleaming. "The closest equivalent we have would be Aurors using potions to test for poisons, but we certainly never dissect. It's taboo in wizarding culture, a remnant of medieval European ideas that we never grew out of after we went into hiding."

Molly frowns. "Well, that's pretty archaic. _Prior incantatem_ only works if you have the right wand. So there's not even some kind of database of the effects of different spells internally?"

" _No,_ " Sherlock draws the word out, enthralled, and steeples his fingers under his mouth in his typical contemplative pose.

She smiles softly to herself, and has a sudden stroke of inspiration. Reaching into her bag, she pulls out a thick paged book ( _Forensic Pathology Techniques Volume III_ ), a birthday gift that had been her bedtime reading for the past few months, and extends it towards him.

"Here," she says simply,."Knock yourself out."

He smiles widely, and it's one of his rare genuine ones. There's no artifice, amusement or arrogance - it's a pure undistorted expression of joy, and she looks at him and can pretend for a moment that she's flying rather than falling.

Their fingers are both clasped on the book between them, he glances down at them and there is a perceptible pause, full of something as incomprehensible as their beating hearts.

She sees his face soften and his smile turn inward. "Molly Hooper," he says quietly, and for once she cannot understand the look that crosses his face.

He looks up and meets her gaze, and doesn't answer the questions he sees in her eyes. "Thank you."

She nods, smiling faintly back, and he takes the book and places it carefully in his bag, with none of the impatience he usually stuffs his belongings in there with.

Her eyes follow him as he walks out; follow his impeccable posture, his fidgeting ink-stained hands, his pristine robes, his untamed curls and his even more untamed eyes and thinks: Sherlock Holmes is a contradiction, and loving him is even more so, both terrible and wonderful in all its ecstasies.

* * *

Mary finds Molly tending the patches in the Herbology garden, the extracurricular habits of a stereotypical Hufflepuff. She's sans gloves though, because she's always loved the feeling of the earth in her fingers.

"Hi," Molly calls softly; though she knows scientifically that plants can't get disturbed, somehow this place has its own sanctity, a magic she can feel in the greenery pulsing around them.

"Hi, Molly." There's something vague in Mary's voice that makes her look up at her friend, in her usual attire of trousers, rolled up robe sleeves and an assured demeanour.

But Molly knows the foolishness of taking this facade for fact, because Mary has always been comfortable with demonstrating every emotion except uncertainty, any state except the in-between. It's different to Sherlock, because she has no qualms about running headfirst into her feelings, but is of the utmost importance to her to portray an unshakable conviction, to smooth over any traces of vulnerability as she does.

"You alright?" Molly asks in concern, wiping her hands on her skirt and standing up to face her.

"Yeah, yeah..."

She's stood at the edge of the greenhouse, as though afraid of being the serpent in a Garden of Eden, arms crossed, eyes resting somewhere above Molly's head.

"I just – " She pauses, and Molly can now definitely hear the hesitation, an indecisiveness uncharacteristic of her in the words she doesn't say. "Walk with me?"

"OK."

So they walk together, the grass swishing under their feet, a chilly breeze incongruous to the sunny day ruffling their hair into tangles. Molly continuously glances at Mary, who strides ahead, staring determinedly at the sky above their heads, and this troubles her, because Mary's never been one who has to hunt for the right words.

Molly comes to an abrupt stop, grabbing Mary's shoulders forcefully. "Calm down, Mary. Just tell me what's going on," she instructs her in measured, soft tones.

Mary nods and runs her hands slowly through her hair, the short blond strands parting at her fingertips.

"Look, Molly..." And suddenly it's like a long built dam has burst, and the words flood out in a torrent as she waves her hands wildly. "The two of you, you and Sherlock, you both feel for each other so deeply and it's so blindingly obvious except you think he doesn't love you, and he keeps pretending he doesn't, and I know you wouldn't believe it if I told you, so I needed to push him, get him to cross the line once so that he stops being so damn scared of it-"

"Wait, wait, _wait_!" Molly says, with an uncharacteristic force that brings Mary to a complete stop.

She runs her hands over her face, and the sheer amount of what Mary implies builds and builds into a slamming force of pressure in her skull, threatening to shatter the long built walls of resolution in her mind.

And yet, to her disgust, there is even a faint bubbling in her stomach that she realises is hope, a hope that must be firmly quashed, a hope that's only tortured her in the past.

 _You both feel for each other so deeply._

 _You think he doesn't love you._

 _I needed to push him -_

And then all the noise in her brain is silenced in an sudden rush of horrifying clarity.

"Mary," she says slowly, trying and failing to keep the dread out of her voice. "What have you done?"

Mary sets her jaw and a grim determination crosses her face; an expression seen throughout history on the faces of self declared martyrs as they sacrifice themselves to their chosen higher cause.

"I spiked him with Amortentia," she admits bluntly. "For you though, no-one else, don't worry," she finishes with a sardonic laugh. The wind whips around them as they face each other, howling in a rush to fill the deadening silence.

No! No no no no no no -

Bile rises in her throat, her body shakes all over.

No no no no no no -

A detaching faintness fills her until all she can see is green, the grass that surrounds her.

No no no no no no -

It's when she feels Mary's hands shaking her that she realises she's sitting, no longer standing, and that she's yelling the words out loud.

Her touch pulls Molly back from her momentary frenzy, and simultaneously triggers a surge of red hot rage that courses feverishly through her veins. She's never felt anything of the kind before, nothing that has blinded her so much to her long held tenancies of consideration, care and kindness, nothing that has controlled her words so passionately and blindly.

"How _dare_ you?" she spits furiously. "What made you think you had the right to do anything so fucking twisted?"

"Like I said, maybe him being controlled by it would make him realise he feels the real thing towards you –"

"Really?" Her laugh is hollow, mocking, spiteful, and Mary flinches from how foreign it is from her lips. "You think watching him chase after me would make me feel better, knowing he's been forced into it and knowing that it's nothing, _nothing_ , like what I feel, nothing like what I long for him to feel?" Her voice becomes empty. "Knowing that the only way he'd ever want me is with a potion rammed down his throat?"

Mary opens her mouth, to elaborate or to contradict, but Molly presses on, "And imagine how he must be feeling? You know how important it is for him to be in control, how much he hates it when he's scared or upset. Imagine how terrifying it's going to be for him, when it wears off and he realises he was entirely powerless to one blinding emotion?"

Her voice grows quieter, more futile. "And what if he did make a move? What if I'd believed it, done anything with someone who'd never consented in the first place." She shudders, clenching her hands into fists. "He'd have to spend the next few years of his life regretting it, and I – I'd have to watch him."

"That's _why_ I told you. I wanted you to know what was going on," Mary beseeches, trying to reach for her, to calm her down, comfort her – it doesn't matter, and Molly shifts away quickly. Mary gives up, her shoulders slumping as she murmurs dejectedly. "I didn't want you to get hurt."

Molly gets up, turning away from her imploring gaze, her eyes resting on the distant treetops of the Forbidden Forest.

"Well that's the thing, Mary." She shrugs in resignation. "You hurt him, and that hurts me."

* * *

 **Really hope you liked it! Reviews are better than Mrs Hudson's badass car. Part 2 already written and coming next week ;-)**


	2. II

**Part 2 is here as promised! Your wonderful reviews on the last one meant the world. Thanks once again to lilsherlockian1975 for beta'ing (aka a pure ray of sunshine). I hope you like it, see you on the other side :-)**

* * *

John Watson is having a strange day.

He'd received a very alarming and cryptic owl from his girlfriend in the morning; and about half his Quidditch team had failed to turn up for trials, claiming "seasonal flu" while forgetting that he was also a Gryffindor and so was also at the common room party last night, and yes that meant he'd witnessed the same half down enough Firewhiskey to induce an alcoholic coma.

But, as it always is with those who believe a day could no longer be any stranger, life decides to vindictively prove them wrong, and John soon discovers this.

A hesitant voice calls his name from the common room, and he puts down the new Quidditch game plan he was scribbling and moves to the dormitory door.

He already knows it's Molly who is stood gingerly at the bottom of the stairs, not just from her voice, but because out of the two women closest to him, only one of them would consider the Gryffindor male dormitory out of bounds.

He jogs down and guides her to a nearby sofa where they sit side by side.

"So who gave you the password this time?" he asks laughingly.

"No idea. Didn't even know them," She smiles. "Honeydukes chocolate is a very effective bribe."

He chuckles, and then gestures to the pile of parchment she's holding with mud stained hands to her chest "What's that?"

"Oh, right." She seems flustered all of a sudden. "Actually, it's what I wanted to talk to you about."

Her gaze wanders around the room until it catches his, and John nods encouragingly for her to continue.

She takes a deep breath. "Basically, Mary thought it would a _wonderful_ idea – " She massages her forehead, and he detects a kind of resigned sarcasm that sounds misplaced in her voice. "- to spike Sherlock with Amortentia."

"What?!" he gapes, and Molly nods grimly.

He immediately sits up straight, so quickly that he almost gives himself whiplash. Images tumble through his mind, of humiliatingly violent declarations in far too public spaces, of him wrestling with his very tall best friend as he pulls him away, of a faceless girl sobbing or slapping him as he (because it'll have to be him) breaks it to her that it was never real, said best friend dragging him out of his bed in the middle of the night to conduct some pointless experiment, just as an excuse to rant about what _he'd_ been subjected to.

The subject of this all being Sherlock Holmes, someone who can barely string together two words of emotional awareness on a good day.

It would be hilarious, perhaps something he'd even pay good money to watch, except he'd be the one dealing with the burden of the fallout.

"Crap," he groans.

Molly catches the intense dread on his face. "It's directed at me," she adds in a monotone.

"Oh."

He slowly leans back as very different, softer emotions fill him, and Molly looks resolutely away. The hints of longing that flicker through the hardened resolution in her eyes amplifies how protective he feels towards her, and he wonders at how Mary would ever consider these unrequited feelings she's had to deal with a subject to be teased about.

It's so entirely uncharacteristic of her that he's too befuddled to be angry, and it causes him to re-examine things, re-evaluate. Moments that were previously lost in the stream of the everyday suddenly present themselves to him, lining up one after the other: a different, softer look in Sherlock's eyes as he stares at her, the way he increasingly mentions her name in conversations, how he buys up half of Honeydukes when she's sick, or how he's only ever shown enthusiasm for Hogsmeade trips when Molly has a date there.

(He should have seen, perhaps, that studying "human courting rituals" wasn't really a good enough reason for the two of them to brew Polyjuice Potion, disguise themselves as Madam Puddifoot waitresses and learn last minute coffee making skills - _just_ to spy on said date.)

And suddenly he's not sure of anything, except two things: one, his girlfriend is a person of quite questionable methods, and two, she knows _exactly_ what she's doing. Mary does everything in all the wrong ways for all the right reasons, it's just the way she cares for people, and he supposes fondly to himself that that is why he loves her.

"You alright?" he says softly to Molly, and she nods tersely, her shoulders hunched.

"It's fine. I'd just rather not see him until it, you know, goes away, just because -" She cuts herself off quickly and lifts the pile of parchment. "I did some research, and though there's no proper antidote for Amortentia, there's a few things you can do to dilute the effects a bit until it wears off."

She thrusts the parchment at him, and he glances over the hastily scribbled instructions with a furrowed brow – Potions has never quite been his strong point.

"I'll see what I can do," he promises.

"Thanks, John," she says gratefully.

"No worries." He stretches his arms upwards and moves to his feet. "I haven't seen him since breakfast when he was spiked, but I'll go find him now and do some damage control."

A hand darts out and grabs his sleeve, and he looks down to see Molly staring at him.

"What makes you think it happened at breakfast?" she says suspiciously.

He holds his hands up. "Don't worry, I didn't know, it's just that," he chuckles. "Well, a very strange owl from Mary about his honey that makes way more sense now."

"Oh. OK," she says slowly, as though mulling something over. "It's just – I saw him just after breakfast, and he seemed...fine."

He frowns. "Actually, come to think of it, I saw him briefly before I went to Quidditch. He _did_ seem fine. Verbally tore my game plan apart actually."

"Yeah, that's very Sherlock." She laughs fondly, and her face breaks into a relieved smile, "He must not have had anything to eat. I know he often skips food when he's working through something in his mind."

John opens his mouth to correct her because, though his day _has_ been very strange, he is positively sure that he didn't hallucinate his best friend spooning honey into his mouth, nor the debate that followed (" _Nobody_ eats honey straight out of a jar." "Preoccupying yourself with my eating habits is a tragic waste of brain capacity, John!").

But then he looks at Molly, the way her hands have unfurled loosely by her sides, how her face has relaxed from the worry lines it was creased into. And something inside, a momentary touch of two threads in the fabric of the universe perhaps, tells him – _don't_.

"Well, at least that's all good then," she sighs, and clambers off the sofa. "Now I've got to go and return some books to the restricted section before Madam Pince realises they're missing."

He shakes head at her in a mock reprimand, and she gives him a smile that's equal parts apologetic and impish.

"I'll find you later, though, and I'll bring the next book in the series," she promises.

John grins: wizards can say what they like, but there is no beating Muggle literature. He remembers Mary's amused laugh when he informed her of this conclusion, and this inspires what he says next.

"Molly!" He calls after her, and she turns around with a quizzical look. He spreads his arms, saying bemusedly. "Once again, I find myself apologising for the utter insanity of my girlfriend-"

"It's fine." She tries to cut him off, but he presses on swiftly.

"Look, I know her methods seem a bit unreasonable..."

Molly's lips press together and she folds her arms against her chest.

"But Molly, please don't hold any of this against her. She's only trying to make you happy, and she thinks – and so do I –" he stresses. "That the two of you _can_ make each other happy if you just sort your crap out."

She shakes her head sharply, but then pauses for a moment and eventually gives him a tired nod. "It's alright, John. I'll be OK with Mary, nothing actually happened and I suppose she did what she did because she cares. She's just acting on what she believes is true. It's not her fault if it isn't."

John mulls over those last words for a while after Molly walks out, remembers how he used to believe them too.

But as images of his two best friends filter through his mind like sunbeams, he wonders how he, and Sherlock, and Molly, had managed to get it so wrong for all these years.

* * *

"If you think storing your broom at the edge of the Forbidden Forest will stop the Slytherins from sabotaging it, you're wrong."

"How did you – never mind, Sherlock, are you alright?"

"For God's sake, Mary has already asked me this twice today, should I be suspecting an assassination attempt gone wrong?"

"No, dammit, just ...you're sure you're feeling nothing funny?"

"Last time I checked, my organs were in perfect working order, probably far sharper, in fact, than your own and not experiencing any health conditions in the vicinity of " _funny"_."

"Alright, if you say so."

"I do. Now, let's go and track down that elusive room that keeps disappearing..."

* * *

 _John – DO NOT EAT ANY OF SHERLOCK'S HONEY AT BREAKFAST... OR AT ANY OTHER POINT. Mary x_

John waves the note in Mary's face as she lounges lazily on the carpet.

"So this deranged owl makes a hell of a lot more sense now," he says accusingly at her, and she tries to keep the laughter out of her voice.

"I know, I know, but come on, imagine how screwed you'd have been if you did." She shrugs amusedly. "You should be thanking me!"

There is a pause. "True," he admits, and then shakes his head helplessly. "Still some explanation would have been nice. I'd prefer to hear your devious schemes first hand."

"I didn't want to risk you telling Sherlock! Or stopping him from taking it, or sabotaging it in any other way..." She raises her eyebrows at his huff, "Come on, that _is_ what you would have done."

"Yeah," he retorts. "Because I'm a sane, moral person -"

"I resent the accusation that the boyfriend _I_ chose is either one of those things," she says happily, and pulls him down by his arm until he collapses beside her on the floor.

He grins in acknowledgement as he leans over her, moving his mouth to hers, but she shifts her head away reprovingly.

"Alright," he groans. "While I might not entirely support the way you went about it... there's something there between the two of them. From his end too. I didn't realise it before, but yeah, thinking about it..."

She nods triumphantly and lifts her head to place a teasing kiss to his lips. Before he can move forward to deepen it, she places a hand over his mouth and raises her eyebrows.

"So you admit I'm right," she says in a challenge.

"Well, you are in Ravenclaw; you're bound to be right some of the time," he murmurs quickly, leaning in once more.

She shakes her head, covering his mouth again. "Almost all of the time," she corrects.

"Most of the time."

"Almost all of the time."

"Almost all of the time," he relents with an amused smile, and she wraps her arms around his neck and pulls his lips to hers.

Eventually, they break apart and she moves her head to lie against his chest. His arm slides around her shoulders and pulls her close to him as they both stare peacefully at the ceiling.

"And to think." She tilts her head up to look merrily into his eyes. "That it was that oblivious sod that basically made this happen."

John chuckles, because whether they like it or not, it's a fact neither of them can deny.

" _Ah, John. This is Mary, recently transferred from Durmstrang," Sherlock says promptly, clearly considering his obligations to the new Ravenclaw fulfilled by the ten minute tour he had given her._

 _She fixes him with an all encompassing look. John clears his throat, entirely lost for words, searching for an ideal first impression on this extremely pretty new student._

 _Sherlock strides away. "Try not to bed her for a week at least," he calls over his shoulder._

 _John's eyes widen, and after some hesitation he starts to stammer out some flailing form of an apology._

 _But her coy smile immediately cuts him off. Mary leans forward and whispers, "I hope you don't do everything he tells you to?"_

They both grin widely at one another, simultaneously caught in a rush of the past.

"But today." Mary's brow creases, and her hands flail listlessly. "He's been..."

"Fine," John finishes in a frown. He glances at her and says quickly. "You sure you brewed the potion right?"

"Well, I didn't make it actually." She leans away, looking decidedly shifty as she mumbles. "I may have stolen some of Slughorn's."

It certainly is quite the confession; John has always been well aware of the pride Mary has in self execution.

"Mary Morstan," he says in mock outrage. "I never thought I'd see the day where you'd take a cop out."

"It's not a cop out!" she exclaims, lightly hitting his torso. "It's being efficient!"

He tries to suppress a laugh, but the way she narrows her eyes tells him that she can most certainly feel it in the shaking of his body against hers.

"Still..." He schools his expression into one of the utmost seriousness, and she allows him the temporary deviation. "Not being affected by Amortentia..."

"I've never heard of it before," she says wondrously. "And he ate some of the honey?"

"Definitely." He nods. "But nothing happened. I mean we all know Sherlock is no ordinary bloke, but that is pretty exceptional."

"It just shouldn't happen." She props her head up on his chest; staring pensively into his eyes as she often does when she's thinking. Evidently finding no answers, she leans back down and says boldly. "I'll look into it."

"I know you will." He grins. That steel set in her eyes is unmistakable, and he knows that the shear strength of her determination will be enough to surpass any logical obstacle.

"And I will brew my own one day," she declares abruptly.

"Right."

"Just you wait; I'll have you writing love letters to Lucius Malfoy for a week..."

He lets a low whistle, and stares at her in awe. "You really are _brutal_ , you know that?"

"Yep," she says cheerfully.

He kisses her until her head spins, and she smiles blissfully as she threads her fingers through his hair. Sentiment, she's come to realise, is only painful when it's not understood.

* * *

Steam obscures the classroom into a blur of bricks and empty chairs. He's alone amongst the cauldrons, and it's a needed retreat from the colliding streams of information that people spark in his brain. Here, loneliness clarifies.

A salamander liver and niffler fur are ushered into the bubbling potion by his wand. Lilac. The wrong colour.

He holds the calculations in his mind so tightly, and tries to mould the outside world to his understanding.

Three. Two. One. _Boom_.

The delight Sherlock Holmes finds in an explosion is only incongruous to those who don't know him. It's a chaos, but one entirely obedient to his every whim and calculation.

Two turns anticlockwise. A dash of Gillywater.

And her face at the door, lit by a showering cascade of sparks from a wand.

Her brown eyes seem to glow through the mist, and though they never demand his gaze, they pulsate a warmth that fills him and creeps up the back of his neck.

"Sherlock?" Molly calls softly.

He doesn't stop working, but he doesn't give her anything but his full and undivided attention. He cannot seem to mute her speech even when he's occupied, as he does most people, and even the smallest details: the way she fiddles with the sleeves of her robes, or how she still drinks in every crevice of the room as though she still cannot quite believe she's here, it all filters through to the forefront of his mind.

She walks slowly towards him, running her fingers across the benches until they stop with a snap at his, coming to fall listlessly by her sides.

"I just wanted to tell you, because in all honesty I doubt anyone else will..." she trails off, sniffing the air appreciatively, and he fights a smile at the way her nose crinkles.

"What are you brewing? Smells amazing." She hums in delight.

Explaining himself out loud has always been far more for his benefit than anyone else's, a way to form maps out of the roads his ideas lead him down. But then he looks at her, peering enthusiastically into the cauldron, the colours of the potion illuminating her face, and he blinks at this strange notion rising up inside of him; that this is all far more for her than for him.

"I'm experimenting with making a potion that precipitates with haemoglobin in the blood and nothing else. The pleasant aroma was a happy side effect," he explains, pouring some into a vial with his wand and passing it over for her to see.

She examines the frothing liquid inside rapturously. "So you could rule out the Unforgivables or any other curses that don't cause bleeding as a cause of death!"

"Yes," he says in satisfaction, and her wide grin at his work creates a confusing but not altogether unpleasant buzz in his chest.

He hastily changes the subject. "You had something you wanted to tell me?"

"Oh, right, yeah," she says rather reluctantly. She tilts the vial back over the cauldron, and with her eyes on the trickling liquid she continues. "You should probably know - someone tried to spike your food with Amortentia today."

The clatter of his wand dropping to the ground echoes through the room, and he stares at her, his eyes wide. Controlled by crazed infatuation, being forced to make a complete fool out of himself in the name of sentiment...though he's been the subject of many a prank before, the very idea of this one fills him with a temporary paralysis.

"Sherlock?" Molly nudges his arm. "You haven't moved for the past ten minutes and it's getting a bit scary now."

The feeling of her fingers dances across his skin, and it jolts him out of his immobile state. He clears his throat and turns away from her to retrieve his wand, berating himself for appearing so perturbed.

By the time he turns back, he is all calm and composure, though under the surface he almost twitches in his eagerness to know the facts.

"So who was it, then?"

Molly hesitates, before saying with an attempted offhandedness, "I don't know."

She's lying to him - [Twisting her plait in her hands, unable to meet his eyes, nods twice after speaking] -

He narrows his eyes. "You know, but you're not telling me. You've never been reluctant for me to retaliate on the tricks played on me before, so this must be someone who you want to protect from my anger. Or someone you believe it would hurt me to know the action was from. John is easy to rule out; he lacks the skill set for acquiring even Firewhiskey, let alone something as contraband as Amortentia. So that leaves..." He sighs. "Of course, Mary."

"Yeah," she says lowly, her lips twisting into an apologetic smile. "I already had, well, quite a strong conversation with her about it. Might be best just to leave it."

"Hmm," he says, knowing that when things like this happen with Mary, she's usually trying to teach him some kind of life lesson, or force him to "realise" something, but he cannot for the life of him understand her purpose this time. He's certain though that a long conversation, and several amusing modifications to her hair products, will soon rectify any confusion.

"But what we can surmise from the lack of nauseating sonnets, bouquets and humiliating declarations from my part is... that it didn't work?" he muses.

"No." She doesn't laugh at his humour as she normally would; instead her voice sounds rather relieved. "You didn't eat what you were supposed to."

"Ah, I see. Thank you, Molly," he says genuinely, because he really is grateful to her for – as always – taking the time to keep him in the loop.

"No worries," she replies, and lifts her bag over her shoulder, shifting her feet, caught between leaving and staying.

And he decides he wants her to stay, though he cannot explain it, just as he cannot comprehend how her mere presence simultaneously calms the collisions of his thoughts and quickens the beats in his chest.

"Just out of interest," he enquires in an attempt to continue the conversation. "Who was the intended recipient of my "violent affections"?" His fingers exaggeratedly form two air quotations on the final phrase as he pulls a face.

"Oh, um." He tilts his head in confusion as she turns very pink. After a slight hesitation, she looks down and says quietly, "It was – me."

He opens his mouth, finds that all of his knowledge on English vocabulary and syntax seems to have been temporarily deleted from his mind palace, and so abruptly closes it again.

With eyes widening, she immediately moves forward, the words almost tumbling over each other in their haste to be known. "It's fine, honestly. Please don't worry about it; it was just some silly joke that never happened. I know what we are, and I'm fine with it, I don't want anything to change -"

\- [Twisting her plait in her hands, unable to meet his eyes, nods twice after speaking] -

"And I..." She closes her eyes briefly and takes a deep breath before opening them again. "Even if it did work, I would never have thought you were in love with me or anything." He hears her try to laugh, but it's rather short and it's rather harsh and it dies rather quickly, "Don't worry."

The vowels and consonants of the words are heard by him, of course, but all they do is vibrate at the front of his skull, unconnected in his mind to any sort of recognition. And yet their conclusion is perfectly valid, and she sounds so certain, that he tries to push aside the feeling of that split second of being caught in the air when missing the last step on the stairs.

"OK." He coughs. "That's good then."

She looks up at him, and something flares in her eyes for a moment, something that dies just as quickly as it burns.

Her shoulders hunch up. "I'll see you later," she says softly, and offers him a tight lipped smile before walking away.

Long after she leaves, he finds his gaze keeps wandering to the arched doorway she'd departed through, replaying the stiff arch of her neck held high, her fingers curling into each other, her plait swinging backwards and forwards as she left, the way she'd faltered at the doorway for a fleeting split second before she did.

But the potion's steam soon obscures the doorway again.

* * *

At midnight, as he lies on top of his bed studying the ceiling, he receives an owl. It's a school one, but oddly enough it screeches and scratches rather urgently at the window before he unfurls the note attached to its leg.

 _Sorry, forgot to say._ _Throw away that jar of honey._ _I know that it'll be painful, but there's always next month! - Molly._

The image of the jar in his bedroom surfaces, and it's a jar with a fair amount of its honey missing. Honey he can almost taste in his mouth.

He frowns.

* * *

Concentrate some sunrays under a magnifying glass. Pick a surface. Do so precisely enough, for long enough, and they'll soon burn a hole through it.

Why the Amortentia had no effect is was - even at first - an unsettling mystery to him. But the longer he concentrates on it, the more the unsettlement becomes a fixation that seems to burn a hole in his head.

It's widely known that Sherlock Holmes enjoys a difficult puzzle. But he soon discovers they are unbearable in himself.

He locks himself away from everyone, practically living in the library, leaving only when he knows his friends are frequenting it, ducking behind bookshelves when they begin to search for him.

It's 1am, the smell of mouldering books surrounds him in a stupor, and his nose is two inches away from the preface of the second edition of Eunice Clearwater's autobiography. And there, with a crippling finality, is where he finds his answer.

 _One or two readers of the last edition deigned to send me some Howlers, complaining that my most famous potion, Amortentia, didn't have the desired effect on their intended. Despite the rather discourteous nature in which they delivered their criticisms, to say the least, I am a witch of her word, and so I conducted several studies to determine the reason for the lack of effect. I can now report that these users of the potion, in short, have the least reason to use it…_

He closes his eyes and sees Molly smiling at him, and there are no grand revelations, just an overwhelming, illogical feeling that he is six again, running through the fields with a wooden cutlass and a hat that floats just above his head.

There is an intangible warmth around his shoulders, and for a moment it's as if she's there behind him, leaning against his back, reading with him, willing him to go on.

And so when does, seeing his answer, it's with a particularly crushing sense of despair, because it's not at all foreign, or strange, and perhaps already half formed before he'd opened his eyes.

 _...Amortentia has no effect on those already in love with the one it is modified for._

Something burning, red-hot and primeval courses through him, and moments later flames spread across the page, his wand still gripped so tightly in his hand his knuckles turn white.

Mary arrives at the same conclusion half a week earlier, simply by visiting Professor Slughorn in his office on an afternoon where the wind rattled the windowpanes.

But then she's always been far better with people than with print. And people, of course, were never his area at all.

(An intellectual choice rather than survivor's instinct, or so he's convinced everyone but himself.)

* * *

The wind courses across the water, rippling it into fleeting semi circles. The lake is so dark, so deep – he can never calculate its exact depth, no matter how hard he tries to estimate the circumference, the way the light refracts – it's simply immeasurable, unfathomable. He wonders how many droplets make it up, wonders at its secrets, how it never overflows.

And that's how Mary finds Sherlock, sat at the edge of the Black Lake, his arms curled around his knees.

She stands still momentarily, watching him with a fondness for her brilliant fool of a best friend. "Of course I'd find you here. _Brooding_."

He says nothing, only looks up slightly, a bare acknowledgement of her presence, of anything around him it seems.

Slowly, cautiously - the movements of children not wanting to scare away a rare bird – she lowers herself into sitting beside him, both of them facing the lake.

"So you know."

He grits his teeth, his hands drop to the ground, digging into the earth. "I _know_ nothing."

"Fibbing again, Sherlock," she says matter-of-factly.

It is that part of the day before sunset, where the sky is bright, but tinged with echoes of pink, traces of a demise yet to come. Yet the air is bitterly cold, and even under the layers of insulation it finds a way to bite them.

She knows that the cold is the reason he's here, not because he truly enjoys it (not with an attire of gloves, a coat, his blue scarf) but because it keeps the other students inside the castle, gives him the isolation he craves, one that brings him no satisfaction.

"So, seventeen and in love," she says, and it should have been mocking, but it wasn't, and instead a slight wonder tinges her voice. "That's something really rare, you know, really..."

She hears him tearing the grass at his feet, the ripping noises becoming faster and faster.

...special."

"No!" he explodes, his face finally torn from its mask of indifference, rising to face her in a terrifying anguish. "I can't feel that way, I just can't – "

"Why not?" she shouts back, frustrated beyond belief. "What exactly is so wrong with it?"

 _A blinding flash from a blurred hand that sears the air. The crimson wool of Redbeard, red, so red, until it's everywhere and he can't make it stop -_

"It's sentimental, it's a foolish distraction from intelligence and reasoning, it would only hold me back..." He clenches his fists, recites the words in attempt to stop the images throbbing in his brain.

"So why are you getting so worked up about it?"

 _The sky turns dark, the air crackles, he's begging. Begging. Begging – who? But the magic slashes again and again and he reaches for Redbeard, spread-eagled on the ground -_

"Because I will hurt her!" he yells, breathing heavily, pressing his hands against the sides of his head.

She steps forward slowly, moves a hand to his wrist to try and still the tremors all over his body, and says softly, "You're hurting her now."

For a while, both of them are stilled into silence. She sees the way he shakes and feels guilt seep into her for her harshness. This is how he has to work through it, she realises, that this is what happens when you try to suppress what should never be caged.

Still, it's difficult, because though she could spot his lies, it had always been Molly who could find the truth in his words.

She takes a deep breath, tries to work through specifics, take it step by step.

"You've always had us you know. You're no stranger to love - you've got friends that love you, who you love. But what you have with Molly is different, and you need to face up to that."

He looks away, taps his hand against his leg three times, needing something to do in the face of not knowing what to do at all. Not for the first time, he wonders what it's like to see things through a non microscopic lens. "Are you in love with John?" he asks her bluntly.

She tilts her head, letting the warmth of her boyfriend's words, embraces, kisses, the facts of his being wash over her. Love, desire, it was all there – but not that all encompassing devotion of being _in_ love, not the irreplaceable certainty that this person is _it_.

"No. No I'm not," she says eventually, having always been truly honest with what's mapped out in her heart. "But I'm young, we haven't been together for long, and we've got time. I care deeply for him, and I think someday I'll get there."

"So I'm the fool, then." He stares straight ahead, and his jaw twitches.

She raises her eyebrows. "I don't know whether you're parroting your brother," she says determinedly. "Or if you actually believe what you're saying, but that is complete and utter bullshit."

His head whips around, and he looks at her with his brow furrowed, his eyes darting around, unbalanced by the absolute dismissal his words are met with.

She looks him fixedly in the eye. "Dumbledore. One of the greatest wizards that ever lived, pretty much the opposite of a fool. And doesn't he always talk about how love is the most powerful magic of all?"

He opens his mouth to point out some of the flaws in some obscure decision the Headmaster made, anything to contradict her or the currents of recognition rising up inside of him at her words.

But then she gives him this minute shake of the head, and suddenly he's losing his footing. The arguments he's always cupped in his hands seem illogical even to him and they start to seep through his fingers.

She watches the wind tousle his hair into disarray, the lights flashing across his eyes, and remembers.

"You know something," she reflects. "I used to be a bit like you. Afraid of caring. I grew up believing that loving someone was the same as condemning them." He stares at her unfathomably, and she stares right back, her words bitterly wielded by experience. "I'm telling you, day by day, it kills you, and one day you'll wake up a shell of who you used to be, and she'll be gone."

He ducks his head, unwilling to let her see the effect of those words on him in the searing pain convulsing his face. All he can do is move away, sit back down just where she found him, and try to pretend that she never came, never catalysed the breakdown of his long held convictions.

And she lets him. But before she walks away, she places her hand softly on his head, and he closes his eyes.

"It's your move, Sherlock." Mary says softly. "It's been your move for a long time."

* * *

Molly steps out of the kitchens, clutching her wrapped bundle of chocolate éclairs to her chest. Defiant to the last against the thuds of music and drunken yells that indicate a common room party, she's very much looking forward to curling up in bed with a favourite book and a sugar rush.

She dashes around the corner, and slams into Sherlock, who quickly darts out a hand to steady her as the éclairs drop to the ground.

"Jesus, Sherlock!" Shock and frustration well up inside of her (and not just because her food is now entirely ruined). She stares at him, her arms crossed. "Where have you _been_?"

"I had to work through something."

She puts a hand to her temple; although in all fairness, she knows it's not strange for him to disappear for a bit if he's preoccupied by a problem. "How did you know I was here?" She sighs.

"You've never been one for all _that_." He shrugs, gesturing vaguely to the noise thundering from the Hufflepuff common room. "I knew sooner or later you'd have to leave."

The way that explanation is so simple, so true and so utterly Sherlock makes her laugh, and she relaxes. "Well, you've got me there."

He smirks at her in turn, and she can't quite keep meeting his gaze in fear of being caught in it. "Was it something to do with the potion you're making? Your problem?"

"Oh. Yes." She thinks his voice sounds stilled for a moment, but she dismisses it as her imagination. "Still pondering a missing ingredient," he finishes quickly.

He tucks his hands into his pockets, and she can't understand the source of his hesitation, the way he keeps glancing at her and glancing away.

But she knows what relaxes her, and he has often derived some semblance of calm and comfort when accompanying her in her self-therapies.

So she gestures down the corridor and offers, "Want to come outside with me?"

"Yes," he answers softly, "Yes I'd like that."

They walk out of the castle, their movements somehow fitting together in the way they remain inches apart but never touch.

The sheer grandiosity of the building never fails to draw her gaze, and the way the moonlight catches the stain glass windows still captivates her a little.

It's different for him, because while for her Hogwarts is the gateway to another world; to him it's a continuation of the stone walled institutions that make up his - that is, until the glimmering of her eyes reminds him to wonder.

But they both catch their breath somewhat at the night sky that awaits them.

Molly smiles happily, and bounds forward to lie on the grass, her arms outstretched. Here, with the earth beneath her fingertips and the stars above her head, she feels held. Her qualms grow fainter with the knowledge of how minute they really are in an ever expansive universe.

He hesitates, looking down at her with a mixture of fear and something warmer, something much stronger, before he clambers a little awkwardly down to lie beside her.

They both gaze upwards at the pinpricks of light that wink back at them, and in the shared intimacy of this experience they feel extraordinarily aware of each other, the space they fill, the space between them.

"Constellations. They're a funny thing, aren't they?" he says faintly.

"Are they?" she teases; he's always had a bit of a philosophical streak, and she savours its rare emergences. "I've always loved them, it's fun to find shapes in the stars, and they all have really beautiful stories to them."

"But they're not objectively true," he stresses. "The Greeks joined up the stars and got Leo, Aquarius, Orion. Yet the Chinese joined them up, and found the Firebird, the Crooked Running Water ." He traces the patterns between the stars, his fingers reaching fervently upwards. "How can you look at the same sky and see something so differently?"

"Well that's what makes them so special, I think," she says softly, "The way you look at things is constantly changing, so it's impossible to be certain that you're seeing the stars in the right way, it's just what _feels_ right to the person looking." She props her face up on her elbow, searching the frustration in his face with an inkling that they've strayed from the subject of astronomy.

His chest rises and falls in the silence, and he mulls over her words, using them to eventually form his. "I'm finding the way I've connected the dots to form my conclusions might not be as right as I once thought. I feel these emotions, and I connected them to indifference, or pain, or loss, when..."

He trails off; caught by the depth of unidentifiable emotion in her eyes, the questions her face has crinkled into. His mind palace conjures up objects haphazardly before his eyes: pages on structuring of a logical argument, a catalogue on the right way to concentrate emotions into magic, even a somehow undeleted article in _Witch Weekly_ on dating advice that he read over Mary's shoulder once. Everything is inadequate.

"I'm sorry – I suppose I don't really know how to do this," he admits.

It's that rare admission of doubt that both confuses and alarms her, far more than even his cryptic words.

He reaches into his pocket and passes her a ripped page, and she unfurls it tentatively, casting a quick _lumos_ with her wand, wondering what on earth she's about to uncover.

"I tried to burn it, but it reformed, I have to concede that in spite of her many faults, Madam Pince has quite a good property protection spell up her sleeves..."

 _...Amortentia has no effect on those already in love with the one it is modified for._

Her eyes widen. He didn't even take the potion. It's impossible. But then she looks at him, just once. She looks past the way he's still rambling, his hands moving wildly, and sees how his face has softened, the glow in his eyes, and the thing is, she's always known him far better than what she believes to be true. She laughs ecstatically, because she knows, she _knows_ , and there's nothing more wonderful than how that bubbles in her heart.

"...and yes I did take the potion, and yes I made sure it wasn't a defect in the potion itself, tested it on some First Years actually, who may or may not be entirely obsessed with you, sorry, but I did drag them to the hospital wing, though I'd be careful just in –"

She trails forward in a daze, tracing the angles and lines in his face. He stills almost instantaneously, his eyes closing, his rapid breaths fluttering across her mouth.

It's impossible to tell who moves first, but maybe it doesn't matter, because they kiss each other in such fervent elation that every other fact is lost to them. She runs her hands through his hair, gasping at the way his lips dance across hers, and he grips her shoulders, entirely overpowered by how the scent of her stills the unrelenting frenzy of his thoughts.

Eventually, they break apart. She slides her arms around his neck, and he presses his forehead against hers.

He gazes at her, blissfully resigned, and says, "I'm one of those teenage idiots now, aren't I?"

"Well," she tells him seriously. "You always were you know." And he can't help the grin that breaks across his face, one that finds its twin in hers.

* * *

Careers advice day for the fifth years. The collective nightmare of every Head of House, who all drain the dregs of their coffees and force themselves to begin.

A girl exits Professor Flitwick's office, eyes too bright to contemplate the future as a linear progression, the moments of her present enough to immerse her. As she rejoins her friends with a cackle of laughter, the leaflet in her hand falls easily to the floor, forgotten.

There it lies, waiting, until a hand hesitantly lifts it to a lonely face, one that hopes to find a home in it.

 _Named in honour of Molly Hooper, who created the department of Magical Forensic Investigation in the Ministry, the Hooper scholarship is available to all those in financial hardship who wish to pursue a career in forensic magic._

 _Molly Hooper is also the co-author of the International Catalogue of Spell-related Bodily Effects, a document that has revolutionised the efficiency of wizarding crime fighting, and the creation of which she shares with Sherlock Holmes, first Consulting Detective to the Auror department._

 _Despite the frenzied speculation of the Daily Prophet, they never married, though their daughter, Isabella Hooper-Holmes, is considered a household name through her invention of the first foolproof antidote to Amortentia._

Fin.

* * *

 **That's all folks! Really hope you liked it as much as I loved writing it. Reviews are better than Moriarty's helicopter dance.**

 **Also was thinking of writing a couple of other one shots on the Sherlock characters in this Potterverse, namely expanding on Mary's past at Durmstrang, and Eurus killing Victor as an obscurus. Thoughts?**


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